Added Signs Folder, and added 4 accepted here signs

2 - Letter Sized Dogecoin accepted here sign (Open QR slot and QR that
forwards to dogecoin.com versions)

2 - 5 inch square sized Dogecoin accepted here sign (Open QR slot and QR
that forwards to dogecoin.com versions)

These files should be able to be used by Creative Commons BY-SA:
https://creativecommons.org/licenses/by-sa/4.0/

Since wanting merchants to use these signs and modify when necessary for their requirements =).

- Updated to have License in folder that pertain to specific files.